Effect of impurity scattering on superconductivity in K2Cr3As3

Impurity scattering in a superconductor may serve as an important probe for the nature of superconducting pairing state. Here we report the impurity effect on superconducting transition temperature Tc in the newly discovered Cr-based superconductor K2Cr3As3. The resistivity measurements show that the crystals prepared using high-purity Cr metal (≥99.99%) have an electron mean free path much larger than the superconducting coherence length. For the crystals prepared using impure Cr that contains various nonmagnetic impurities, however, the Tc decreases significantly, in accordance with the generalized Abrikosov-Gor’kov pair-breaking theory. This finding supports a non-s-wave superconductivity in K2Cr3As3.